1. The Institute for Occupational Health, Yonsei University College of Medicine, Korea
2. Department of Preventive Medicine, Yonsei University College of Medicine, Korea
3. Department of Preventive Medicine, Wonju College of Medicine, Yonsei University, Korea
4. Department of Preventive Medicine, Seoul National University College of Medicine, Korea
5. Institute Occupational and Environmental Medicine, Wonju College of Medicine, Yonsei University, Korea